Periodontitis comes as the second most common dental disease problem in society. Aggregatibacter actinomycetemcomitans bacteria belongs to anaerobic gram-negative group known as the main cause of agrresive periodonitis. Pineapple (Ananas comosus) is a widely spread plant which can live in highlands as well as in lowlands throughout the globe. Flavonoid and bromelain enzyme found in pineapple (Ananas comosus) skin can be used as a bacterial growth inhibitor. Objective: The purpose of this study was to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of pineapple (Ananas comosus) skin extract on the growth of Aggregatibacter actinomycetemcomitans. Method: This study was an in vitro, semi-laboratory experiment Antibacterial effect test was conducted using liquid dilution method on Brain Heart Infusion (BHI) medium and solid dilution method on Triton Soya Agar (TSA) medium Pineapple (Ananas comosus) skin extract was serially diluted into some concentrations: 100%, 50%, 25%, 12.5%, 6.25%, 3.125%, 1.56%, 0.78%, and 0.39%. Minimum inhibitory concentration and minimum bactericidal concentration were determined by observing the growth of Aggregatibacter actinomycetemcomitans on both medium. Result: Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) was found at 6,25%. Conclusion: Pineapple (Ananas comosus) skin extract was effective in inhibiting and eliminating Aggregatibacter actinomycetemcomitans